As an athlete. . .

hello people gud day! As an athlete, how do you gain a self-confidence when the game comes or when the game started? because you know, ever since i joined our team in volleyball everytime there's a game, i felt nervous then my body becomes weak i can't even jump or use spike to the ball and when my nervous' gone it's too late cuz the game is almost over. So anyone would like to suggest how to gain or improve my self-confidence?

I usually say to myself when I am about to start a game that I will win it..
I say it a few times in myself, make fists and close my eyes.. After that I am usually more confident than before :D
Maybe it will help for you too ^^ Try it :)
Have a good day :)